Electrosurgical apparatuses often include a cannula having an electrically insulated region and an electrically exposed conductive region for delivering energy to a tissue to form a lesion, and an elongate member, for example a stylet, for inserting into and occluding the lumen of the cannula. Alternatively, as described in U.S. Ser. No. 10/274,074 (US 2003/0093007 “Wood”), the stylet may provide a means for cauterizing tissue in addition to the means for cauterizing tissue associated with the cannula, and imaging enhancers may be placed on the stylet to assist in visualizing an apparatus.
In some procedures, fluoroscopy is used in order to visualize the cannula when it is inside a patient's body. However, when energy is delivered from a cannula to form a lesion in the body, the lesion generally does not form at the distal end of the cannula. Rather, the lesion forms around the entire electrically exposed conductive region of the cannula. Furthermore, in apparatuses which are cooled, the lesion may form away from the distal end of the cannula, and may not contact the electrically exposed conductive region of the cannula at all. In addition, when a radiopaque marker is affixed to the distal end of a cannula, the shape of the distal end is modified, which may require that extra force be applied when the apparatus is inserted into the patient's body.
Thus, it would be beneficial to provide an apparatus that provides a visual reference indicating where a lesion will form within the body, and which does not interfere with the insertion of the apparatus into the patient's body.